Birdlike (5)
I believe the answer is:
avian
'birdlike' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for avian that I've seen before include "Like rails, for example" , "Pertaining to or characteristic of birds" , "Birdlike" , "Like a booby" , "Relating to birds" .)